A variety of designs are already known in practice, wherein a compacting device is connected downstream for compacting (condensing) the fiber material (fiber strand) discharged from the drawing system unit. Subsequent to such a compacting device, the condensed fiber material is fed to a twist generation device after passing a clamping point. In the case of a ring spinning machine, for example, such a twist generation device is composed of a traveler revolving on a ring, wherein the generated yarn is wound onto a rotating tube. Suctioned revolving, perforated suction drums or revolving aprons provided with perforations are essentially used as compacting units. Using appropriate inserts inside the suction drum, or inside the revolving aprons, a special suction area is defined on the compacting element. Such inserts can be provided with appropriately shaped suction slots, for example, to which a negative pressure is applied, whereby a corresponding air current is generated at the periphery of the respective compacting element. In particular, protruding fibers are integrated into the yarn as a result of this air current, which is oriented substantially transversely to the transport direction of the fiber material.
In the known approaches, the fiber material discharged from the drawing system unit is guided above, or also below, the compacting devices that are used. In particular, for use on a ring spinning machine, it is necessary to provide an additional clamping point downstream of the suction zone so as to obtain a twist stop.
Such devices have been shown and described, for example, in the publications EP 947 614 B1, DE 10 2005 010 903 A1, DE 198 46 268 C2, EP 1 612 309 B1, DE 100 18 480 A1 and CN 1712588 A. These cited publications essentially involve fixedly installed compacting units, which are fixedly installed downstream of the respective drawing system. These compacting units are in part driven by way of special drive shafts, which are disposed over the length of the spinning machine and which are in driving engagement with either a suction roller or a revolving apron, or by way of a fixedly installed drive connection to appropriately disposed pressure rollers of the compacting unit.
In practice, it is necessary to retrofit existing spinning machines comprising a conventional drawing system unit with such a compacting device so as to ensure the possibility of producing high-quality yarns with these machines as well. Therefore, devices have been proposed by way of which conventional drawing systems can be retrofitted with such a compacting device. One such example can be found in DE 102 27 463 C1, for example, wherein the roller stand of the drawing system unit is extended in order to mount an additional drive roller provided for driving the retrofitted compacting device, which is likewise disposed on this extension. The drive roller extends over the entire length of the spinning machine. Attaching and installing such a retrofit unit is very time-consuming and inflexible. This means that desired dismantling to a standard drawing system without a compacting device is, in turn, very time-consuming.
A design is known from CN 101613896 A in which an additional element is screwed to the roller stand to extend the roller stand of the drawing system. Moreover, the publication DE 100 50 089 C2 shows a design comprising a compacting device that is provided for subsequent attachment to a conventional drawing system unit.
A device is known from CN 2 851 298 Y in which a compacting roller, together with a twist stop roller, is accommodated in a bearing element, which is connected by way of a plate to a pivotable weighting arm of a drawing system device via screws. In the mounted and locked position, the driving motion is transmitted via friction from a delivery roller connected directly to a drive and the pressure roller associated with the delivery roller to the compacting roller and the twist stop roller. The compacting device shown here is likewise provided for subsequent installation on existing drawing system units of spinning machines having no condensing. The compacting unit shown here is attached to an existing drawing system unit by way of a screw connection, and threading on the axle of the pressure roller is relatively time-consuming and requires an additional adjustment of the distances. The connection to a negative pressure source likewise must be established separately.
In the above-described designs, the suction elements that are associated with a defined compacting region for condensing the fiber material are subjected to a negative pressure by way of additionally disposed pipes, which are connected to a negative pressure source.
So as to simplify such compacting devices, allowing easy and fast installation on conventional drawing system units without requiring the installation of additional drive elements, PCT/CH2011/000280, which has not yet been previously published, proposes a design in which the compacting element in the form of a suction drum and the clamping roller are rotatably mounted on a shared support (support element), which is detachably attached to the spinning machine by way of attachment means. So as to establish a driving engagement between the drawing system rollers and the detachably attached compacting device, the compacting device is pivoted about a pivot axis in the direction of the delivery roller pair of the drawing system via the support element, wherein a respective friction wheel that is coaxially attached to the respective suction drum enters a frictional engagement (by way of friction) with the bottom roller of the delivery roller pair of the drawing system. The compacting device is held in this driving engagement by way of appropriately disposed spring elements (for example, on the weighting arm of the drawing system).
In the present example, the support element is provided for rotatably mounting two suction drums which are disposed coaxially and next to each other and which are attached downstream of two neighboring drawing system units, which are referred to as a twin drawing system. A twin drawing system shall be understood to mean two neighboring drawing system units, the pressure rollers of which are loaded by way of a shared pressure bar.
A suction channel for applying a negative pressure to the compacting elements is provided inside the support element (support). A first end of the suction channel is connected to the respective compacting element, and the second end thereof ends in the region of the support element at which the support element is attached to the spinning machine in the assembled position. The second end of the suction channel inside the support element forms a coupling point for connecting a further air channel, which is connected to a main channel. This means that, in the proposed design, the support element (support) serves both as a receptacle and bearing element for the compacting elements (for example, rotatably mounted suction drums having fixedly installed suction inserts) and as a channel for applying a negative air pressure to the corresponding suction inserts of the compacting units.